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Abstract
Targeted temperature management (TTM) is used frequently in patients with a variety of diseases, especially those who have experienced brain injury and/or cardiac arrest. Shivering is one of the main adverse effects of TTM that can often limit its implementation and efficacy. Shivering is the body's natural response to hypothermia and its deleterious effects can negate the benefits of TTM. The purpose of this article is to provide an overview of TTM strategies and shivering management.
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Abstract
Evidence from animal models indicates that lowering temperature by a few degrees can produce substantial neuroprotection. In humans, hypothermia has been found to be neuroprotective with a significant impact on mortality and long-term functional outcome only in cardiac arrest and neonatal hypoxic-ischemic encephalopathy. Clinical trials have explored the potential role of maintaining normothermia and treating fever in critically ill brain injured patients. This review concentrates on basic concepts to understand the physiologic interactions of thermoregulation, effects of thermal modulation in critically ill patients, proposed mechanisms of action of temperature modulation, and practical aspects of targeted temperature management.
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Abstract
Evidence from animal models indicates that lowering temperature by a few degrees can produce substantial neuroprotection. In humans, hypothermia has been found to be neuroprotective with a significant impact on mortality and long-term functional outcome only in cardiac arrest and neonatal hypoxic-ischemic encephalopathy. Clinical trials have explored the potential role of maintaining normothermia and treating fever in critically ill brain injured patients. This review concentrates on basic concepts to understand the physiologic interactions of thermoregulation, effects of thermal modulation in critically ill patients, proposed mechanisms of action of temperature modulation, and practical aspects of targeted temperature management.
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Affiliation(s)
- Fred Rincon
- Division of Critical Care and Neurotrauma, Department of Neurology, Sidney-Kimmel College of Medicine, Thomas Jefferson University, 909 Walnut Street, 3rd Floor, Philadelphia, PA 19107, USA; Division of Critical Care and Neurotrauma, Department of Neurological Surgery, Sidney-Kimmel College of Medicine, Thomas Jefferson University, 909 Walnut Street, 3rd Floor, Philadelphia, PA 19107, USA.
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Petitjeans F, Leroy S, Pichot C, Geloen A, Ghignone M, Quintin L. Hypothesis: Fever control, a niche for alpha-2 agonists in the setting of septic shock and severe acute respiratory distress syndrome? Temperature (Austin) 2018; 5:224-256. [PMID: 30393754 PMCID: PMC6209424 DOI: 10.1080/23328940.2018.1453771] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 03/11/2018] [Indexed: 12/12/2022] Open
Abstract
During severe septic shock and/or severe acute respiratory distress syndrome (ARDS) patients present with a limited cardio-ventilatory reserve (low cardiac output and blood pressure, low mixed venous saturation, increased lactate, low PaO2/FiO2 ratio, etc.), especially when elderly patients or co-morbidities are considered. Rescue therapies (low dose steroids, adding vasopressin to noradrenaline, proning, almitrine, NO, extracorporeal membrane oxygenation, etc.) are complex. Fever, above 38.5-39.5°C, increases both the ventilatory (high respiratory drive: large tidal volume, high respiratory rate) and the metabolic (increased O2 consumption) demands, further limiting the cardio-ventilatory reserve. Some data (case reports, uncontrolled trial, small randomized prospective trials) suggest that control of elevated body temperature ("fever control") leading to normothermia (35.5-37°C) will lower both the ventilatory and metabolic demands: fever control should simplify critical care management when limited cardio-ventilatory reserve is at stake. Usually fever control is generated by a combination of general anesthesia ("analgo-sedation", light total intravenous anesthesia), antipyretics and cooling. However general anesthesia suppresses spontaneous ventilation, making the management more complex. At variance, alpha-2 agonists (clonidine, dexmedetomidine) administered immediately following tracheal intubation and controlled mandatory ventilation, with prior optimization of volemia and atrio-ventricular conduction, will reduce metabolic demand and facilitate normothermia. Furthermore, after a rigorous control of systemic acidosis, alpha-2 agonists will allow for accelerated emergence without delirium, early spontaneous ventilation, improved cardiac output and micro-circulation, lowered vasopressor requirements and inflammation. Rigorous prospective randomized trials are needed in subsets of patients with a high fever and spiraling toward refractory septic shock and/or presenting with severe ARDS.
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Affiliation(s)
- F. Petitjeans
- Critical Care, Hôpital d'Instruction des Armées Desgenettes, Lyon, France
| | - S. Leroy
- Pediatric Emergency Medicine, Hôpital Avicenne, Paris-Bobigny, France
| | - C. Pichot
- Critical Care, Hôpital d'Instruction des Armées Desgenettes, Lyon, France
| | - A. Geloen
- Physiology, INSA de Lyon (CARMeN, INSERM U 1060), Lyon-Villeurbanne, France
| | - M. Ghignone
- Critical Care, JF Kennedy Hospital North Campus, WPalm Beach, Fl, USA
| | - L. Quintin
- Critical Care, Hôpital d'Instruction des Armées Desgenettes, Lyon, France
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Alfonsi P, Passard A, Guignard B, Chauvin M, Sessler DI. Nefopam and Meperidine Are Infra-Additive on the Shivering Threshold in Humans. Anesth Analg 2014; 119:58-63. [DOI: 10.1213/ane.0000000000000193] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Evers MM, Toonen LJA, van Roon-Mom WMC. Ataxin-3 protein and RNA toxicity in spinocerebellar ataxia type 3: current insights and emerging therapeutic strategies. Mol Neurobiol 2014; 49:1513-31. [PMID: 24293103 PMCID: PMC4012159 DOI: 10.1007/s12035-013-8596-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 11/14/2013] [Indexed: 01/10/2023]
Abstract
Ataxin-3 is a ubiquitously expressed deubiqutinating enzyme with important functions in the proteasomal protein degradation pathway and regulation of transcription. The C-terminus of the ataxin-3 protein contains a polyglutamine (PolyQ) region that, when mutationally expanded to over 52 glutamines, causes the neurodegenerative disease spinocerebellar ataxia 3 (SCA3). In spite of extensive research, the molecular mechanisms underlying the cellular toxicity resulting from mutant ataxin-3 remain elusive and no preventive treatment is currently available. It has become clear over the last decade that the hallmark intracellular ataxin-3 aggregates are likely not the main toxic entity in SCA3. Instead, the soluble PolyQ containing fragments arising from proteolytic cleavage of ataxin-3 by caspases and calpains are now regarded to be of greater influence in pathogenesis. In addition, recent evidence suggests potential involvement of a RNA toxicity component in SCA3 and other PolyQ expansion disorders, increasing the pathogenic complexity. Herein, we review the functioning of ataxin-3 and the involvement of known protein and RNA toxicity mechanisms of mutant ataxin-3 that have been discovered, as well as future opportunities for therapeutic intervention.
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Affiliation(s)
- Melvin M. Evers
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333ZA Leiden, The Netherlands
| | - Lodewijk J. A. Toonen
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333ZA Leiden, The Netherlands
| | - Willeke M. C. van Roon-Mom
- Department of Human Genetics, Leiden University Medical Center, Albinusdreef 2, 2333ZA Leiden, The Netherlands
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Correia ACDC, Silva PCB, da Silva BA. Malignant hyperthermia: clinical and molecular aspects. Rev Bras Anestesiol 2014. [PMID: 23176990 DOI: 10.1016/s0034-7094(12)70182-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
CONTENT Malignant hyperthermia (MH) is a potentially lethal pharmacogenetic disorder that affects genetically predisposed individuals. It manifests in susceptible individuals in response to exposure to Inhalant anesthetics, depolarizing muscle relaxants or extreme physical activity in hot environments. During exposure to these triggering agents, there is a rapid and sustained increase of myoplasmic calcium (Ca(2+)) concentration induced by hyperactivation of ryanodine receptor of skeletal muscle (RyR1), causing a profound change in Ca(2+) homeostasis, featuring a hypermetabolic state. RyR1, Ca(2+) release channels of sarcoplasmic reticulum, is the primary locus for MH susceptibility. Several mutations in the gene encoding the protein RyR1 have been identified; however, other genes may be involved. Actually, the standard method for diagnosing MH susceptibility is the muscle contracture test for exposure to halothane-caffeine (CHCT) and the only treatment is the use of dantrolene. However, with advances in molecular genetics, a full understanding of the disease etiology may be provided, favoring the development of an accurate diagnosis, less invasive, with DNA test, and also will provide the development of new therapeutic strategies for treatment of MH. Thus, this brief review aims to integrate molecular and clinical aspects of MH, gathering input for a better understanding of this channelopathy.
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Affiliation(s)
- Ana Carolina de Carvalho Correia
- Laboratório de Tecnologia Farmacêutica Prof. Delby Fernandes de Medeiros, Universidade Federal da Paraíba, João Pessoa, PB, Brasil.
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Park SM, Mangat HS, Berger K, Rosengart AJ. Efficacy spectrum of antishivering medications. Crit Care Med 2012; 40:3070-82. [DOI: 10.1097/ccm.0b013e31825b931e] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Choi HA, Ko SB, Presciutti M, Fernandez L, Carpenter AM, Lesch C, Gilmore E, Malhotra R, Mayer SA, Lee K, Claassen J, Schmidt JM, Badjatia N. Prevention of shivering during therapeutic temperature modulation: the Columbia anti-shivering protocol. Neurocrit Care 2011; 14:389-94. [PMID: 21210305 DOI: 10.1007/s12028-010-9474-7] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND As the practice of aggressive temperature control has become more commonplace, new clinical problems are arising, of which shivering is the most common. Treatment for shivering while avoiding the negative consequences of many anti-shivering therapies is often difficult. We have developed a stepwise protocol that emphasizes use of the least sedating regimen to achieve adequate shiver control. METHODS All patients treated with temperature modulating devices in the neurological intensive care unit were prospectively entered into a database. Baseline demographic information, daily temperature goals, best daily GCS, and type and cumulative dose of anti-shivering agents were recorded. RESULTS We collected 213 patients who underwent 1388 patient days of temperature modulation. Eighty-nine patients underwent hypothermia and 124 patients underwent induced normothermia. In 18% of patients and 33% of the total patient days only none-sedating baseline interventions were needed. The first agent used was most commonly dexmeditomidine at 50% of the time, followed by an opiate and increased doses of propofol. Younger patients, men, and decreased BSA were factors associated with increased number of anti-shivering interventions. CONCLUSIONS A significant proportion of patients undergoing temperature modulation can be effectively treated for shivering without over-sedation and paralysis. Patients at higher risk for needing more interventions are younger men with decreased BSA.
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Affiliation(s)
- H Alex Choi
- The Neurological Institute of New York, Columbia University College of Physicians and Surgeons, New York, NY, USA
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10
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Abstract
PURPOSE OF REVIEW The review covers the main aspects of thermoregulation physiology and highlights the implications for therapeutic hypothermia trials. Prevention of shivering and other hypothermia side-effects is of key importance because controlling thermoregulatory responses may be essential for demonstrating neuro-protective properties of hypothermia in several pathologic conditions in which its role is still uncertain, such as in traumatic brain injury and stroke. RECENT FINDINGS Several recommendations and clinical reviews have been produced in the past 2 years about the application and feasibility of therapeutic hypothermia. Many drugs have been tested in healthy volunteers and anaesthetized patients to abolish shivering but the best protocol for managing side-effects has not yet been defined. A possible strategy might be to simultaneously apply physical methods, such as skin warming, and combination drug therapy. Different drug protocols can be applied, depending on the nature of the care setting. SUMMARY During moderate hypothermia treatment, conducted in an intensive care environment, shivering can be treated with sedatives, opioids (meperidine in particular), and α2-agonists, combined with active skin counter-warming. However, new randomized controlled clinical trials in intensive care patients are required to improve our knowledge regarding this treatment.
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Weant KA, Martin JE, Humphries RL, Cook AM. Pharmacologic options for reducing the shivering response to therapeutic hypothermia. Pharmacotherapy 2011; 30:830-41. [PMID: 20653360 DOI: 10.1592/phco.30.8.830] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Recent literature has demonstrated significant improvements in neurologic outcomes in patients who have received induced hypothermia in the setting of out-of-hospital cardiac arrest. Through multiple metabolic mechanisms, the induction of hypothermia slows the progression and devastation of transient cerebral hypoxia. Despite these benefits, the desired reduction in core temperature is often a challenging venture as the body attempts to maintain homeostasis through the induction of thermoregulatory processes aimed at elevating body temperature. Shivering is an involuntary muscular activity that enhances heat production in an attempt to restore homeostasis. For successful induction and maintenance of induced hypothermia, shivering, as well as other thermoregulatory responses, must be overcome. Several pharmacologic options are available, either used alone or in combination, that safely and effectively prevent or treat shivering after the induction of hypothermia. We conducted a PubMed search (1966-March 2009) to identify all human investigations published in English that discussed pharmacologic mechanisms for the control of shivering. Among these options, clonidine, dexmedetomidine, and meperidine have demonstrated the greatest and most clinically relevant impact on depression of the shivering threshold. More research in this area is needed, however, and the role of the clinical pharmacist in the development and implementation of this therapy needs to be defined.
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Affiliation(s)
- Kyle A Weant
- Pharmacy Services, University of Kentucky HealthCare, University of Kentucky, Lexington, KY 40536-0293, USA.
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Schleelein LE, Litman RS. Hyperthermia in the pediatric intensive care unit--is it malignant hyperthermia? Paediatr Anaesth 2009; 19:1113-8. [PMID: 19694974 DOI: 10.1111/j.1460-9592.2009.03120.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To determine the characteristics of calls made to the Malignant Hyperthermia Association of the United States (MHAUS) Hotline regarding pediatric patients in the intensive care unit setting. AIM Retrospective, cohort study conducting analysis of included cases to identify the cause of elevated temperature in the pediatric intensive care unit. BACKGROUND The etiology of hyperthermia in the pediatric intensive care unit (ICU) is multifactorial and often difficult to diagnose. METHODS/MATERIALS Review of all MHAUS logs for the years 1997-2005 for children, 18 years of age and younger, with elevated temperature presenting in the intensive care setting. RESULTS Sixty-three of 1883 (3.3%) calls met inclusion criteria and these cases were characterized. Patient temperature values ranged from 38.0 to 45.0 degrees C. Malignant hyperthermia (MH) was considered 'definite' in five cases and 'probable' in three cases. An infectious diagnosis was given to 16 cases, and a central fever was diagnosed in nine cases. The diagnosis was unknown in the remaining 30 cases. Dantrolene was administered prior to the Hotline call in 32 cases. The recommendation to continue or stop dantrolene varied according to the clinical situation. In six cases, the Hotline expert recommended initiation of dantrolene. In 17 cases, the Hotline expert recommended initiation or continuation of dantrolene as a nonspecific antipyretic, even though MH was not considered as a leading diagnosis. CONCLUSIONS Cases of elevated temperature in children in an intensive care unit setting reported to the MHAUS Hotline were rarely considered to be MH related. Although MH does not represent a significant portion of diagnoses related to hyperthermia, when hyperthermia occurs in children exposed to anesthetic agents, MH should be considered in the differential diagnosis.
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Abstract
Core body temperature is normally tightly regulated by an effective thermoregulatory system. Thermoregulatory control is sometimes impaired by serious illness, but more typically remains intact. The primary autonomic defenses against heat are sweating and active precapillary vasodilation; the primary autonomic defenses against cold are arteriovenous shunt vasoconstriction and shivering. The core temperature triggering each response defines its activation threshold. Temperatures between the sweating and vasoconstriction thresholds define the inter-threshold range. The shivering threshold is usually a full 1 degrees C below the vasoconstriction threshold and is therefore a "last resort" response. Both vasoconstriction and shivering are associated with autonomic and hemodynamic activation; and each response is effective, thus impeding induction of therapeutic hypothermia. It is thus helpful to accompany core cooling with drugs that pharmacologically induce a degree of thermal tolerance. No perfect drug or drug combination has been identified. Anesthetics, for example, induce considerable tolerance, but are rarely suitable. Meperidine-especially in combination with buspirone-is especially effective while provoking only modest toxicity. The combination of buspirone and dexmedetomidine is comparably effective while avoiding the respiratory depression association with opioid administration.
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Metabolic benefits of surface counter warming during therapeutic temperature modulation*. Crit Care Med 2009; 37:1893-7. [DOI: 10.1097/ccm.0b013e31819fffd3] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Dantrolene mediates vasorelaxation in cerebral vasoconstriction: a case series. Neurocrit Care 2008; 10:116-21. [PMID: 18696267 DOI: 10.1007/s12028-008-9132-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 07/30/2008] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Cerebral vasoconstriction syndromes such as vasospasm after subarachnoid hemorrhage (SAH) and trauma, or Call-Fleming syndrome are difficult to treat, and can lead to substantial disability and death. Dantrolene, a ryanodine receptor antagonist, inhibits intracellular calcium release from the sarco-endoplasmic reticulum. We examined the effect of dantrolene on middle cerebral artery (MCA) blood flow velocities as measured by transcranial Doppler (TCD). METHODS Three consecutive patients with elevated MCA TCD velocities receiving dantrolene (2.5 mg/kg i.v. q6h) were retrospectively reviewed. Average MCA peak systolic, mean flow velocities, and the pulsatility index (PI) before and after the dantrolene infusion were compared within patients. Systemic physiological parameters (blood pressure, heart rate, central venous pressure, intracranial pressure, body temperature, and cooling water temperature) were retrospectively collected 6 h before and after the dantrolene infusion. RESULTS MCA peak systolic velocities (mean +/- SE) for the three patients were 297 +/- 3, 248 +/- 8, and 268 +/- 19 cm/s before dantrolene and 159 +/- 9, 169 +/- 8, and 216 +/- 12 cm/s after dantrolene. Average mean flow velocities showed the same trend. Interestingly, the PI increased slightly from 0.6, 0.52, and 0.67 before dantrolene, to 1.17, 0.71, and 0.77 after dantrolene. Systemic physiological parameters remained stable in all three patients. CONCLUSION Dantrolene attenuated cerebral vasoconstriction as measured by TCD without altering systemic physiological parameters. This suggests that intracellular calcium release from ryanodine channels in smooth muscle might play a role in vasospasm. A prospective study is underway to test this hypothesis.
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Muehlschlegel S, Sims JR. Dantrolene: mechanisms of neuroprotection and possible clinical applications in the neurointensive care unit. Neurocrit Care 2008; 10:103-15. [PMID: 18696266 DOI: 10.1007/s12028-008-9133-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Accepted: 07/30/2008] [Indexed: 10/21/2022]
Abstract
Calcium plays a central role in neuronal function and injury. Dantrolene, an inhibitor of the ryanodine receptor, inhibits intracellular calcium release from the sarco-endoplasmic reticulum. We review the available data of dantrolene as a potential neuroprotective agent and briefly summarize its other pharmacologic effects that may have potential applications for patients in the neurointensive care unit (NICU). Areas with the need for continued research are identified.
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Affiliation(s)
- Susanne Muehlschlegel
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01605, USA
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Arpino PA, Greer DM. Practical pharmacologic aspects of therapeutic hypothermia after cardiac arrest. Pharmacotherapy 2008; 28:102-11. [PMID: 18154480 DOI: 10.1592/phco.28.1.102] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract Therapeutic hypothermia has emerged as an effective means of improving neurologic outcomes among cardiac arrest survivors. To achieve optimal results, clinicians must understand and anticipate potential adverse effects of cooling and provide rigorous monitoring and/or pharmacologic interventions as appropriate. Using pharmacotherapy to counter adverse effects of cooling or to treat an intrinsic process under hypothermic conditions requires understanding how hypothermia will influence the clinical effects of the drug, including the drug's pharmacokinetics and pharmacodynamics. The pharmacologic aspects of therapeutic hypothermia in relation to physiology and adverse effects are reviewed.
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Affiliation(s)
- Paul A Arpino
- Department of Pharmacy, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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Ohta H, Maruyama M, Tanabe Y, Hara T, Nishino Y, Tsujino Y, Morita E, Kobayashi S, Shido O. Effects of redecoration of a hospital isolation room with natural materials on stress levels of denizens in cold season. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2008; 52:331-340. [PMID: 17957390 DOI: 10.1007/s00484-007-0125-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 09/21/2007] [Accepted: 09/22/2007] [Indexed: 05/25/2023]
Abstract
We investigated the effects of redecoration of a hospital isolation room with natural materials on thermoregulatory, cardiovascular and hormonal parameters of healthy subjects staying in the room. Two isolation rooms with almost bilaterally-symmetrical arrangements were used. One room (RD) was redecorated with wood paneling and Japanese paper, while the other (CN) was unchanged (with concrete walls). Seven healthy male subjects stayed in each room for over 24 h in the cold season. Their rectal temperature (T(re)) and heart rate, and the room temperature (T(a)) and relative humidity were continuously measured. Arterial blood pressures, arterial vascular compliance, thermal sensation and thermal comfort were measured every 4 h except during sleeping. Blood was sampled after the stay in the rooms. In RD, T(a) was significantly higher by about 0.4 degrees C and relative humidity was lower by about 5% than in CN. Diurnal T(re) levels of subjects in RD significantly differed from those in CN, i.e., T(re)s were significantly higher in RD than in CN especially in the evening. In RD, the subjects felt more thermally-comfortable than in CN. Redecoration had minimal effects on cardiovascular parameters. Plasma levels of catecholamines and antidiuretic hormone did not differ, while plasma cortisol level was significantly lower after staying in RD than in CN by nearly 20%. The results indicate that, in the cold season, redecoration with natural materials improves the thermal environment of the room and contributes to maintaining core temperature of denizens at preferable levels. It also seems that redecoration of room could attenuate stress levels of isolated subjects.
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Affiliation(s)
- Hiromi Ohta
- Department of Environmental Physiology, Faculty of Medicine, Shimane University, 89-1 Enya-cho, Izumo 693-8501, Japan
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Abstract
Hypothermia is a potent neuroprotectant and induced hypothermia holds great promise as a therapy for acute neuronal injury. Thermoregulatory responses, most notably shivering, present major obstacles to therapeutic temperature management. A review of thermoregulatory physiology and strategies aimed at controlling physiologic responses to hypothermia is presented.
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Affiliation(s)
- M Asim Mahmood
- University of South Alabama Stroke Center, Suite 10-I, 2451 Fillingim Street, Mobile, AL 36617, USA
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Podranski T, Bouillon T, Schumacher PM, Taguchi A, Sessler DI, Kurz A. Compartmental Pharmacokinetics of Dantrolene in Adults: Do Malignant Hyperthermia Association Dosing Guidelines Work? Anesth Analg 2005; 101:1695-1699. [PMID: 16301243 DOI: 10.1213/01.ane.0000184184.40504.f3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Dantrolene is the only drug proven effective for prevention and treatment of malignant hyperthermia (MH). Current dosing recommendations are based on noncompartmental analyses and are largely empiric. They are also divergent, as evidenced by differing recommendations from the Malignant Hyperthermia Association of the United States (MHAUS) and European Sources. We determined the compartmental pharmacokinetics of dantrolene, simulated the concentration time course based on currently recommended dosing, and suggest an optimal regimen. Nine volunteers (55-89 kg) received IV infusions of dantrolene (5 mg/kg over 30 min followed by 0.05 mg.kg(-1) . h(-1) for 5 h). Venous blood samples were drawn for up to 60 h, and dantrolene plasma concentrations were determined by reverse phase, high-performance liquid chromatography. One, two, and three compartmental models were fitted to the data, and a covariate analysis was performed. All calculations were performed with NONMEM using the population approach. The data were adequately described by a two-compartment model with the following typical variable values (median +/- se): volumes of distribution V1= 3.24 +/- 0.61 L; V2= 22.9 +/- 1.53 L; plasma clearance CL el= 0.03 +/- 0.003 L/min; and distributional clearance CL dist= 1.24 +/- 0.22 L/min. All parameters were scaled linearly with weight. Simulations of European recommendations for treatment of MH lead to plasma concentrations converging to 14-18 mg/L within 24 h. Simulating MHAUS guidelines (intermittent bolus administration) yielded peak and trough plasma concentrations ranging from 6.7-22.6 mg/L. Based on our findings, we propose an infusion regimen adjusted to the initial bolus dose(s) required to control symptoms. This strategy maintains the individualized therapeutic concentrations and improves stability of plasma concentrations.
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Affiliation(s)
- Tobias Podranski
- *Department of Anesthesiology, University of Bern, Switzerland; †Department of Anesthesia, Washington University, St. Louis, Missouri; ‡Outcomes Research™ Institute, University of Louisville, Kentucky
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Abstract
Experimental evidence and clinical experience suggest that mild hypothermia protects numerous tissues from damage during ischemic insult. However, the extent to which hypothermia becomes a valued therapeutic option will depend on the clinician's ability to rapidly reduce core body temperature and safely maintain hypothermia. To date, general anesthesia is the best way to block autonomic defenses during induction of mild-to-moderate hypothermia; unfortunately, general anesthesia is not an option in most patients likely to benefit from therapeutic hypothermia. Induction of hypothermia in awake humans is complicated by both the technical difficulties related to thermal manipulation and the remarkable efficacy of thermoregulatory defenses, especially vasoconstriction and shivering. The most effective thermal manipulation devices are generally invasive and, therefore, more prone to complications than surface methods. In an effort to inhibit thermoregulation in awake humans, several agents have been tested either alone or in combination with each other. For example, the combination of meperidine and buspirone has already been applied to facilitate induction of hypothermia in human trials. However, pharmacological induction of thermoregulatory tolerance to cold without excessive sedation, respiratory depression, or other serious toxicity remains a major focus of current therapeutic hypothermia research.
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Affiliation(s)
- Anthony G Doufas
- Outcomes Research Institute, Department of Anesthesiology and Perioperative Medicine, University of Louisville, Louisville, KY, USA.
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Wadhwa A, Sengupta P, Durrani J, Akça O, Lenhardt R, Sessler DI, Doufas AG. Magnesium sulphate only slightly reduces the shivering threshold in humans. Br J Anaesth 2005; 94:756-62. [PMID: 15749735 PMCID: PMC1361806 DOI: 10.1093/bja/aei105] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Hypothermia may be an effective treatment for stroke or acute myocardial infarction; however, it provokes vigorous shivering, which causes potentially dangerous haemodynamic responses and prevents further hypothermia. Magnesium is an attractive anti-shivering agent because it is used for treatment of postoperative shivering and provides protection against ischaemic injury in animal models. We tested the hypothesis that magnesium reduces the threshold (triggering core temperature) and gain of shivering without substantial sedation or muscle weakness. METHODS We studied nine healthy male volunteers (18-40 yr) on two randomly assigned treatment days: (1) control and (2) magnesium (80 mg kg(-1) followed by infusion at 2 g h(-1)). Lactated Ringer's solution (4 degrees C) was infused via a central venous catheter over a period of approximately 2 h to decrease tympanic membrane temperature by approximately 1.5 degrees C h(-1). A significant and persistent increase in oxygen consumption identified the threshold. The gain of shivering was determined by the slope of oxygen consumption vs core temperature regression. Sedation was evaluated using a verbal rating score (VRS) from 0 to 10 and bispectral index (BIS) of the EEG. Peripheral muscle strength was evaluated using dynamometry and spirometry. Data were analysed using repeated measures anova; P<0.05 was statistically significant. RESULTS Magnesium reduced the shivering threshold (36.3 [SD 0.4] degrees C vs 36.6 [0.3] degrees C, P = 0.040). It did not affect the gain of shivering (control, 437 [289] ml min(-1) degrees C(-1); magnesium, 573 [370] ml min(-1) degrees C(-1); P=0.344). The magnesium bolus did not produce significant sedation or appreciably reduce muscle strength. CONCLUSIONS Magnesium significantly reduced the shivering threshold. However, in view of the modest absolute reduction, this finding is considered to be clinically unimportant for induction of therapeutic hypothermia.
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Affiliation(s)
- Anupama Wadhwa
- Assistant Professor, OUTCOMES RESEARCH™ Institute and Department of Anesthesiology and Perioperative Medicine, University of Louisville
| | - Papiya Sengupta
- Research Fellow, OUTCOMES RESEARCH™ Institute, University of Louisville
| | - Jaleel Durrani
- Resident, Department of Anesthesiology and Perioperative Medicine, University of Louisville
| | - Ozan Akça
- Assistant Director OUTCOMES RESEARCH™ Institute, Assistant Professor Department of Anesthesiology and Perioperative Medicine, Director Neurosciences Intensive Care Unit, University of Louisville
| | - Rainer Lenhardt
- Assistant Director OUTCOMES RESEARCH™ Institute, Assistant Professor Department of Anesthesiology and Perioperative Medicine, Director Neurosciences Intensive Care Unit, University of Louisville
| | - Daniel I. Sessler
- Vice Dean for Research, Associate Vice President for Health Affairs, Director OUTCOMES RESEARCH™ Institute, Lolita & Samuel Weakley Distinguished University Research Chair, Professor of Anesthesiology and Pharmacology, University of Louisville
| | - Anthony G. Doufas
- Assistant Professor and Director of Research, Department of Anesthesiology and Perioperative Medicine and OUTCOMES RESEARCH™ Institute, University of Louisville
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